Ketene dimer paper sizing compositions including acyl compound extender and paper sized therewith



March 28, 1967 IOOOO R. J. KULICK ETAL 3,311,532

KETENE DIMER PAPER SIZING COMPOSITIONS INCLUDING ACYL COMPOUND EXTENDERAND PAPER SIZED THEREWITH Filed March 17, 1965 HEXADECYL KETENE DIMERADDED BASED ON DRY WEIGHT 0F FIBERS STEARIC ACID ADDED BASED ON' WEIGHT0F HEXADECYL KETENE DIMER INVENTORS. RUSSELL J. KULICK EDWARD STRAZDINSANTHONY R. SAVINA ATTGRNEY United States Patent KETENE DIMER PAPERSIZING (ZOMPOSITIONS ENCLUDIING ACYI. CGMPOUND EXTENDER AND PAPER SEIZEDTHEREWITH Russell Eoseph Kuiicir, Port Qhester, N.Y., and EdwardStrazdins and Anthony Ralph Savina, Stamford, Coma, assignors toAmerican Cyauamid Company, Stamford, (101111., a corporation of MaineFiled Mar. 17, 1065, Ser. No. 440,584 16 filaims. (Cl. 162179) This is acontinuation-in-part of our copending application Ser. No. 254,157,filed Jan. 28, 1963, now abandoned.

The present invention relates to paper-sizing compositions comprising ahydrophobic paper-sizing ketene dimer and an acyl compound which acts asextender therefor. The invention includes the manufacture of sized paperby use of these compositions, and the resulting paper.

Hentrich et al. US. Patent No. 2,411,860 (1946) discloses that paper isrendered water-resistant when treated with higher ketene dimers, andArlt US. Patent No. 2,901,371 (1959) discloses that in theemulsification of these ketene dimers, to prepare them for use as sizingagents for paper, the higher fatty acids are particularly advantageousemulsifying agents.

The discovery has now been made that the effectiveness of the higherketene dimers as paper-sizing agents is greatly enhanced when they arepresent on the cellulose fibers of the paper in conjunction with acomparatively large amount of a hydrophobic substantiallywater-insoluble saturated substantially straight-chain acyl compound. Wehave found that in preferred embodiments these acyl compounds (whichinclude the higher fatty acids) improve the sizing action of the ketenedimers in three principal respects.

(1) They act as extenders for the ketene dimers; that is, they permitthe amount of paper-sizing ketene dimer which has been previouslyrequired to achieve a given level of sizing, to be decreased. We havefound that by this means the amount of ketene dimer in a typical sizingoperation can be decreased by about 50%75%. Since suitable acylcompounds are cheap and freely available and since paper-sizing ketenedimers are comparatively expensive, the present invention permits amajor decrease in the cost of manufacturing sized paper by the use ofketene dimers.

(2) They act as accelerators for ketene dimer sizes; that is, theyincrease the rate at which these ketene dimers develop their sizing whenthey are heated during drying. We have found it possible by use ofpreferred acyl compounds to develop in two minutes of heating at about100 C. substantially the same sizing from paper-sizing ketene dimers asis developed by 30 minutes of similar heating in the absence of suchcompound.

(3) They act as fortifying agents for the ketene dimers; that is,although they impart comparatively no sizing themselves, theysubstantially increase the ultimate sizing imparted by the ketene dimer.Ketene dimers are outstandingly effective sizes for paper, capable ofimparting a very high degree of Water and lactic acid resistance topaper. The present invention achieves an absolute improvement in theamount of ultimate sizing imparted by the paper-sizing ketene dimers.

The foregoing improvements do not become apparent unless the weight ofthe added acyl compound is at least about of the weight of the ketenedimer.

The invention thus in its principal aspect resides in compositionsconsisting essentially of a paper-sizing ketene dimer and an efiectiveextending amount, in excess of about 10%, based on the weight thereof,of a hydrophobic substantially water-insoluble, substantiallystraight-chain acyl compound as extender for the ketene dimer. Forms orstates in which the components of the composition are present aredescribed below.

The invention includes the manufacture of sized paper by use of theaforesaid components, and the present invention broadly consists in theutilization of substantial amounts of an acyl compound (as hereinaftermore fully described) in conjunction with one or more paper-sizingketene dimers in any of the established paper-making processes. Theinvention is thus essentially an improvement in established paper-makingprocesses. This is an important advantage because the invention does notrequire any change in established methods for the manufacture of sizedpaper by the use of ketene dimer as sizing agents.

Broadly, then, the process comprises depositing a papersizing ketenedimer on cellulose fibers as size together with an effective amount ofthe acyl compound as extender therefor, followed by heating the fibersto develop the sizing properties of the ketene dimer thereon. Theinvention does not primarily depend upon the particular means employedfor depositing the components of the fibers.

The invention also resides in the resulting paper, which is composed ofcellulose fibers sized by a uniformly distributed reacted content of apaper-sizing ketene dimer and by an effective uniformly distributedunreacted surface content of the acyl compound in excess of about 10% ofthe weight of the ketene dimer as extender therefor. The acyl compoundis evidently in uniform admixture with the reacted ketene dimer.

The range over which the acyl compounds act as extender is broader thanthe range over which they act as accelerator and fortifying agent.Accordingly, in the claims the amount of acyl compound present or used(as the case may be) is defined in terms of the action of the acylcompounds as extender, and is sometimes designated as effectiveextending amounts, and it will be understood that this includes in eachinstance the amount in which the acyl compounds act as accelerator andfortifying agent.

The hydrophobic, substantially water-insoluble, saturated, substantiallystraight-chain acyl compounds used in the present invention are ingeneral the acids, higher fatty acids (i.e., fatty acids which contain12 carbon atoms or more) and the anhydrides, amides, acid chlorides andaldehydes of these acids. By the term substantially Water-insoluble wemean that the compounds dissolve in water to the extent of less than 1%and preferably less than 0.1%, and by the term substantially straightchain, we mean that the compounds are either precisely straight chain orthat whatever branching they contain is of no significant consequencefrom the point of view of the amount of sizing which is imparted bythese compounds.

Suitable acyl compounds include lauric, palmitic, stearic, and arachidicacids, their anhydrides, amides, aldehydes and acid chlorides, andmixtures thereof.

The acyl compounds are most advantageously used alone, but they may beused in admixture with minor amounts of highly branched chain orunsaturated acyl compounds. For example, they may be used in admixturewith min-or amounts of oleic acid, oleamide and the branched chaincarboxylic acids formed by oxidation of petroleum hydrocarbons, whichare tolerated.

The invention is illustrated by the drawing, which shows the effect ofstearic acid as extender, as accelerator, and as fortifying agent forthe sizing action of hexadecyl ketene dimer. The data are presented inthe form of curves A and B and point E and were obtained as follows:

A series of handsheets was prepared by beater addition of hexadecylketene dimer (prepared from commercial stearic acid) alone or inadmixture with stearic acid as sizing agents. The agents were added ascationic emulsions. In each instance the weight of the hexadecyl ketenedimer (or hexadecyl ketene dimer-stearic acid mixture) was 0.2% of thedry weight of the fibers; the ratio of stearic acid to the ketene dimeris set forth on the lower abscissa. Since in each instance the weight ofsizing composition added was constant, the amount of hexadecyl ketenedimer decreased in proportion as the amount of stearic acid increased.The amount of hexadecyl ketene dimer added in each instance as apercentage of the dry weight of the fibers is shown along the abscissaat the top of the drawing.

One set of handsheets was dried for two minutes at 230 F. (correspondingto the cure obtained on a typical paper-making machine), after which thesizing of the sheets was determined by the use of 20% aqueous lacticacid applied at 100 F. under a head of 12". The results were plotted andcurve A drawn.

The second set of handsheets was dried for /2 hour at 223 R, whichdeveloped substantially all the sizing which the additives were capableof imparting. The results were plotted and curve B drawn. Furtherdetails of the process are shown in Example 5 below.

The effect of the acyl compound as extender when the size has completedapproximately maximum cure is illustrated by dotted line C whichconnects points B1 and B2 of curve B. Since the line is substantiallyhorizontal, it shows that in the runs performed, substantially the samesizing is obtained by the use of a hexadecyl ketene dimer and stearicacid mixture wherein the weight of the stearic acid is 100% of theweight of the ketene dimer (point B2) as is obtained by the use ofketene dimer alone (point B1).

The maximum elfective amount of the acyl compound as extender atcomplete cure has not been ascertained but evidently is substantially inexcess of 100% of the weight of the ketene dimer since the dottedposition of curve B shows that a substantial amount of sizing isobtained when the weight of the acyl compound is 125 150% of the weightof the ketene dimer. A part of the acyl compound thus evidently acts asinert diluent.

The effect of the acyl compound as extender during the initialdevelopment of the sizing action of the ketene dimer is illustrated byhorizontal line E connecting points A1 and A3. Line E shows thatsubstantially as good oif the machine sizing is obtained by use of 0.2g. of a hexadecyl ketent dimer-stearic acid mixture wherein the weightof the latter is about 233% the weight of the former as is obtained byan equal weight of hexadecyl ketene dimer alone.

The effect of the stearic acid as accelerator is illustrated by pointsA2 and B1 of the drawing. These points show that the presence of about67% of stearic acid, based on the weight of the ketene dimer, causes7800 seconds of sizing to develop in 2 minutes at 230 F. (point A2), andthat 9650 seconds of sizing are developed by the ketene dimer alongafter /2 hour at 223 F. (point B1).

The effect of stearic acid as fortifying agent is illus trated by lineF, which connects points B2 and G. The latter point represents theapproximate ultimate sizing of paper manufactured by addition of 0.1% ofhexadecyl ketene dimer in the same manner as the handsheets from whichthe data of curve A were obtained, and point B2 represents theapproximate ultimate sizing of corresponding paper prepared by beateraddition of 0.1% of the ketene dimer plus 0.1% of stearic acid. itappears from line F that the stearic acid caused the sizing to increasefrom 900 seconds to 9,600 seconds, an increase of approximately 8,700seconds. This increase is a measure of the fortifying action of the acylcompound.

Curve A shows that close to maximum acceleration of the development ofsizing per increment of acyl compound present occurs when the weight ofthe acyl compound is about %25% of the weight of the ketene dimer andthat virtually maximum absolute acceleration 4. is obtained when theweight of the stearic acid is 50% to 75% of the weight of the ketenedimer.

Curve B shows that valuable sizing results are obtained even when thewei ht of the acyl compound is in excess of the optimum amounts asextender, accelerator and tortifying agent. The excess amount evidentlyacts essentially as diluent.

The data of the drawing illustrate typical results so far obtained.Somewhat different curves are obtained depending particularly on theparticular ketene dimer and acyl compound used, the total Weight ofketene dimer and acyl compound added (based on the dry weight of thefibers), the pH of the paper-making suspension and the electrostaticsign of the emulsions and the particular emulsifying agents presenttherein. The eifect of these variables cannot be calculated, and in eachinstance, therefore, the optimum or the maximum effective amount of theacyl compound as extender or activator and the best choice ofemulsifiers can best be determined by a series of laboratory trials.

The components of the compositions of the present invention may bepresent in several forms or states. They may thus be present as a dryblend of discrete papersizing ketene dimer particles and particles of asuitable acyl compound. If desired, the components may be in solutionform and for this purpose benzene or chloroform are suitable solvents.Moreover, the components may be in unitary homogeneous state such as inthe composition which is formed by melting the lretene dimer and theacyl compound together, and then chilling the resulting solution, sothat the acyl compound is present as a solution in the ketene dimer (orvice versa).

The dry compositions mayinclude one or more emulsifying agents for theketene dimer and the acyl compound. The emulsifying agent may benon-ionic, cationic, or anionic. When the acyl compound is a fatty acid,acid chloride, or anhydride, the anionic emulsifying agent may bereplaced by an equivalent amount of an alkali metal alkali (for examplesodium bicarbonate) so as to convert a portion of the acyl compound to asoap when the composition is emulsified with water.

The compositions may contain materials customarily employed in themanufacture of paper which are not incompatible therewith. They may thuscontain supplementary inert extenders such as silica or silica gel;starch; pigments and dyes; supplementary sizing agents as for examplewax size; scents; hydrophobic, cyclic compounds as for example rosin;and mold growth inhibitors.

The compositions may be prepared for use in the same manner as thepaper-sizing ketene dimers have been prepared for use in the past.

Thus the compositions may be dissolved in a volatile organic solvent toform a solution suitable for use as an impregnant.

The compositions are more economically prepared for use by conversion tofluid aqueous emulsions. The emulsions are conveniently prepared byintensively agitating the ketene dimer and the acyl compound together ina volume of water containing one or more emulsifying agents. Thetemperature of the water is preferably above the melting points of theketene dimer and the acyl compound. The emulsifying agent may beanionic, cationic, or non-ionic. The resulting emulsion may behomogenized, after which the emulsion is rapidly cooled to preventformation of aggregates. The invention does not depend upon theparticular way in which the emulsions are formed. Alternatively, the twocomponents may be emulsified separately and mixed.

The cationic emulsions may be prepared as is disclosed in Arlt US.Patent No. 3,046,186. The non-ionic and anionic emulsions may beprepared as is disclosed in Downey US. Patent No. 2,627,477 and inOsberg US. Patent No. 2,785,067. Any of the common cationic, anionic andnon-ionic emulsifiers may be used for the preparation of the respectiveemulsions.

Sized paper may be manufactured in any convenient way by use of thesolution and emulsions referred to above.

Preformed paper may be sized by impregnation with a volatile organicsolution or with an aqueous anionic, cationic or non-ionic emulsion ofthe ketene dimer and the acyl compound, followed by heating the paper todevelop the sizing properties of the ketene dimer-acyl compoundcombination.

Sized paper may be manufactured by use of the foregoing emulsion asbeater additives. In such process the ketene dimer and the acylcompounds as single or as separate emulsions are added to an aqueoussuspension of cellulose paper-making fibers, after which the suspensionis sheeted to form a wet web and the web is heated to develop the sizingproperties of the additives.

The ketene dimer and the acyl compound may be added as a single emulsionwhich may be cationic, anionic o-r non-ionic.

The cationic emulsions are self-substantive, and therefore when thistype of emulsion is employed the fibrous suspension may be sheetedimmediately thereafter.

The anionic emulsions are best employed in conjunction with awater-soluble cationic polymer. The polymer can be added first insufficient amount to render the fibers cationic, or can be added afterthe anionic emulsion.

It is often advantageous to add the ketene dimer as two separateemulsions, which may be of the same or of opposite electrostatic sign.Where both emulsions are cationic or anionic, the process steps are ashave been respectively described above. When they are of oppositeelectrostatic sign, they act as mutual retention aids.

The amount of sizing composition to be added in each instance is mostconveniently found by trial because a given amount of the sizingcomposition produces somewhat difierent sizing depending upon theparticular pulp employed, its pH, and the amount and identity of anycationic material present. In general, we have found that the mostsizing per unit weight of the composition added occurs when thecomposition is added in the range of 0.2% to 0.4% based on the dryweight of the fibers, so that this range is preferred. However, valuablesizing results are obtained by the use of smaller amounts and by use oflarger amounts, at least up to about 1%. The par ticular amount of thecomposition employed in any instance, however, is not a principalfeature of the invention.

It is advantageous to maintain the paper at a temperature in the rangeof 200 F.-250 F. or higher, up to the temperature where the fibersbecome degraded, until the sizing properties of the ketene dimer-acylcombination have been developed at least to a substantial extent,because the development of substantial sizing during this heating issure evidence that ultimate sizing of which the composition is capableof causing will develop on normal storage of the paper thereafter. Inpreferred embodiments of the present invention, this occurs within /z2minutes when the paper is maintained in the above-stated temperaturerange. This is about sufiicient time for webs of ordinary basis weightto become substantially dry and corresponds to the'time required forpaper to pass through the drying section of a typical paper-makingmachine.

The invention will be further illustrated by the examples, which arespecific embodiments of the invention and are not to be construed aslimitations thereon.

6 EXAMPLE 1 The following illustrates the effect of stearic acid asextender for hexadecyl ketene dimer. The agents are applied as organicsolutions to preformed paper.

Solution A.-O.2 g. of hexadecyl ketene dimer is dissolved in 100 g. ofbenzene.

Solution B.0.1 g. of hexadecyl ketene dimer and 0.1 g. of stearic acidare dissolved in 100 g. of benzene.

A sheet of pure untreated cellulose paper (blotting paper) is immersedin solution A for two minutes, and a similar sheet is immersed insolution B for the same length of time. Both sheets are allowed to dryat room temperature for one hour. The sheet which was dipped in solutionA is composed of cellulose fibers at least partly coated with hexadecylketene dimer. The sheet which was dipped in solution B is composed ofcellulose fibers at least partly coated with a mixture consisting ofhexadecyl ketene dimer and stearic acid in 1:1 weight ratio. The sheetsare then heated at 230 F. for /2 hour to develop the ultimate sizingproperties of the agents therein.

Sheet A contains about 0.2% by weight of hexadecyl ketene dimer andsheet B about 0.1% by weight each of hexadecyl ketene dimer and ofstearic acid.

Both sheets possess substantially equal resistance to penetration by 20%aqueous lactic acid solution. The stearic acid in sheet B consequentlyacted as extender for the ketene dimer.

EXAMPLE 2 The following illustrates the comparative effect of severalacidic, hydrophobic substantially water-insoluble, substantiallystraight-chain acyl compounds as accelerators of the development of thewater-resistance imparted by paper-sizing ketene dimers. The agents areapplied as non-ionic emulsions to preformed paper.

A series of emulsions is prepared as'follows. To 200 g. of Water at C.is added 2 g. of the condensation product of 10 mols of ethylene oxidewith 1 mol of p-octylphenol (Triton X). The solution is agitated in aWaring Blender running at top speed, and there is slowly run in 15 g. ofmolten (80 C.) sizing composition, shown in the table below. After 30'seconds of agitation, 20 g. of the resulting emulsions are removed andare diluted to 0.27% size concentration by addition to 480 g. of coldwater.

Weighed sheets of untreated cellulose absorbent paper (blotting paper)are immersed in the respective emulsions for 2 minutes, after which thesheets are removed. Excess liquid is removed by pressing the paperbetween similar damp paper. The sheets are reweighed. They contain 0.20%of size based on the dry weight of the fibers.

The sheets are dried by two passes of one minute each over a laboratorydrum drier having a surface temperature of 230 F. From prior experienceit is known that this drying does not develop more than a fraction ofthe sizing properties of hexadecyl ketene dimer, in the absence of anaccelerator.

The sizing imparted by the emulsions was determined by the Cobb test,wherein the sheets are weighed, contacted on one side with 20% aqueouslactic acid as test fluid at 20 C. for 15 minutes, and reweighed. Sizingis reported as the grams of lactic acid solution which are absorbed per25 cm? of paper surface.

1 HKD =hexadecyl ketene dimer.

2 Size to accelerator.

= Based on dry weight of the paper. 4 Paper was saturated with water.

The results show that the presence of the acyl compounds (stearic acid,stearic anhydride and stearamide) causes a major acceleration in therate at which papersizing ketene dimers develop their sizing properties.

EXAMPLE 3 The following illustrates the manufacture of sized paper insimilar manner using a different non-ionic emulsifying agent and anadditional acyl compound.

A series of four emulsions is prepared by adding in each instance 15 g.of a molten (80 C.95 C.) sizing composition as shown in the table belowto 200 cc. of water at 80 C. containing 1 ml. of polyoxyethylenesorbitol hexaoleate (a non-ionic emulsying agent manufactured by AtlasChemicals Industries) in a Waring Blender operating at full speed. Afterone minute the resulting emulsions are diluted to 0.42% solids byaddition of water at about C.

Four sheets of untreated cellulose paper (blotting paper) are weighed,soaked in the respective emulsions for five minutes, and removed. Excessemulsion is taken up by placing the sheets between blotting paperpreviously damped with water.

The sheets are reweighed and are found in each instance to contain 0.30%of sizing composition based on the dry weight of the fibers.

The sheets are dried by one pass of one minute over a laboratory drumdrier having a surface temperature of 230 F.

Sizing is determined by the Cobb test, as described above, except thatwater is used as the test fluid.

To 100 g. of a 3% by weight hot (80 C.) aqueous solution of awater-soluble cationic starch in a Waring Blendor running at top speedis slowly added first 0.15 g. of sodium lignosulfonate and then 10.0 g.of molten (80 C.) hexadecyl ketene dimer. After 60 seconds the resultingemulsion is rapidly cooled by dilution to 1% with cold water.

The procedure is repeated twice, in the first instance 25% (2.25 g.) ofthe ketene dimer being replaced by myristic acid and in the secondinstance the same amount of the ketene dimer being replaced with stearicacid.

Sized paper is prepared by use of these emulsions by forming an aqueoussuspension of a 30:70 bleached hardwood: bleached softwood kraft pulp ata consistency of 0.6% and a pH of 7. Aliquots are taken from thissuspension and to each is respectively added sufiicient of the foregoingemulsions to provide 0.12% of sizing composition solids (hexadecylketene dimer plus any fatty acid added) on the dry weight of the fibers.There is then added suificient of an aqueous solution of cationic starchto provide 0.4% of cationic starch based on the dry weight of thefibers. The pH of the aliquots is adjusted to 6.3 and the suspensionsare sheeted to form handsheets at a basis weight of 100 lbs. (25" x"/500 ream).

The handsheets are then dried by two passes of 1 minute each over alaboratory drum drier having a surface temperature of 230 F. Fromprevious experience it is known that this drying is insufiicient in theabsence of accelerator to develop more than a small fraction of theultimate sizing of the hexadecyl ketene dimer.

The sizing of the resulting handsheets is determined by the lactic aciddrop test, wherein drops of blue-tinted 20% aqueous lactic acid solutionare applied to the paper at 20 C. Sizing is reported as the average timerequired for the drops to be absorbed by the paper.

Results are as follows:

Sizing Composition 1 HKD =hexadecyl ketene dimer. Of size toaccelerator. Based on dry weight of paper.

b Percent hexadecyl ketene dimer in sheet, based on dry weight of ers. 2Percent accelerator in sheet, based on dry weight of fibers.

The results show that replacement of ,6, of the ketene dimer with anacyl compound causes a major acceleration in the development of sizing.

EXAMPLE 4 The following shows the comparative effect of two differenthigher fatty acids as accelerators for hexadecyl ketene dimer as papersize. The following also illustrates the manufacture of sized paper byuse of these agents employed as beater additives in aqueous cationicemulsion state.

The results show that in general longer chain acyl compounds are betteraccelerators than shorter chain acyl compounds.

- EXAMPLE 5 The following illustrates the effect of the acyl compoundsboth as accelerators and extenders of the sizing action of paper-sizingketene dimers.

A series of emulsions is prepared by the method of Example 4. In theseries, the ketene dimer is replaced by successively larger incrementsof stearic acid, but in each instance the total weight of the sizingcomposition added (ketene dimer plus stearic acid) is constant.

Sized handsheets are prepared by the standard test method of Example 4.One set of handsheets is given a short cure (2 minutes at 230 F.) tosimulate commercial machine drying. The second set of thandsheets isgiven a long cure /2 hour at 223 F.) to develop substantially all thesizing which the composition is capable of imparting. The sizing of thesheets is determined by use of 20% aqueous lactic acid solution, appliedby penescope at a temperature of F. under a head of 12".

Results are as follows:

Sizing Composition 1 Sizing (Seconds) Run No.

HKDzSA Percent Percent Percent Percent Short Cure Long Cure Wt. Ratio111(1) 2 SA 2 HKD+SA 3 HKD+SA 2 100:0 0. 20 None None None 900 9, 60095:5 0. 19 0.01 5. 5 0. 20 3,000 9, 600 90:10 0. l8 0. 02 ll. 0. 20 5,600 10, 400 75:25 0. 15 0. 33. 3 0. 20 7. 400 11, 450 50:50 0. l0 0.100. 0 0. 20 7, 850 9, 650 30:70 0. 06 0. 14 233. 3 0. 20 None None 1HKD=hexadeeyl ketene dimer; SA=stearic acid. 2 Based on dry weight ofthe fibers. 3 Based on weight of the hexadecyl ketene dimer present.

The results are shown graphically in the drawing, curve powder forms ananionic emulsion when 10 g. is slowly A being a graph of the resultsobtained with the short cure and curve B being a graph of the resultsobtained with the long cure.

From other tests it is known that prolongation of cure does notnecessarily cause continued increase in the waterrepellance imparted bythe sizing composition. These tests have shown that when large amountsof extender are present based on the weight of the ketene dimer, sizingvalues slowly decrease when the paper is held at curing temperatures forcomparatively long periods of time. The optimum cure time can be readilyfound by laboratory trial, and our own tests suggest that curing thepaper for half an hour at 105 C. will generally result in development ofmaximum sizing values.

EXAMPLE 6 The following illustrates the preparation of a homogeneouscomposition according to the present invention consisting essentially ofa paper-sizing ketene dimer and a fatty acid as accelerator therefor.

A melt of hexadecyl ketene dimer and stearic acid in l:1 /2 Weight ratiohaving a temperature of 90 C. is flowed upon a rotating drum chillerprovided with a doctor blade. The surface temperature of the chiller is30 C. Homogeneous crisp flakes are obtained.

The flakes are powdered by passage through a roller crusher. Theresulting powder is free-flowing.

Both the flakes and the powder emulsify readily when slowly poured intointensively-agitated water at 90 C. which contains an emulsifying agent.

EXAMPLE 7 The foregoing procedure is repeated except that stearicanhydride is employed in place of the stearic acid. A similarcomposition is obtained.

EXAMPLE 8 The procedure of Example 6 is repeated except that stearamideis employed in place of the stearic acid and the temperature of the meltis about 100 C. A similar composition is obtained.

EXAMPLE 9 The following illustrates the preparation of an ionicself-dispersible composition according to the present invention.

To 100 g. of the homogeneous free-flowing powdery blend of hexadecylketene dimer and stearic acid (1: 1 /2 weight ratio) of Example 6 isadded 1.5 g. of sodium lignosulfonate and 33 g. of a water-solublecationic starch, and the mixture is ball-milled for a few minutes. Theresulting powder emulsifies when 10 g. of the powder is slowly addedwith intensive agitation to 100 cc. of water at 90 C.

EXAMPLE 10 The following illustrates the preparation of a dry blend of apaper sizing which forms an anionic emulsion.

To 100 g. of the powdered hexadecyl ketene dimerstearic acid blend ofExample 6 is added 1.0 g. of sodium bicarbonate. The mixture isball-milled. The resulting added with intensive agitation to 100 cc. ofwater at EXAMPLE 11 To an aqueous suspension of beaten cellulosepapermaking fibers at 0.6% consistency is added 0.5% based on the dryweight of the fibers, of a cationic polyamidopolyamine-epichlorohydrinwet strength resin of Keim 7 U8. Patent No. 2,926,154 as a 1% aqueoussolution, followed by sufficient of the emulsion described above toprovide 0.3% of sizing solids based on the dry weight of the fibers. Thesize is precipitated on the fibers by the adsorbed cationic resin andyields about as well-sized paper as is obtained by a corresponding sizeprepared by use of an equal amount of the hexadecyl ketene dimer aloneEXAMPLE 12 The following illustrates a preferred method for themanufacture of sized paper according to the present invention byaddition of a cationic cellulose-substantive hexadecyl ketenedimer-stearic acid emulsion to beater pulp, the amount of stearic acidbeing sufficient to'provide excellent acceleration of cure and extensionof the effect of the ketene dimer.

An aqueous suspension of beaten cellulose papermaking fibers is preparedat 0.6% consistency and at pH 7 and to this is added 0.2%, based on thedry weight of the fibers of a 50:50 by weight ratio of the dilutedhexadeeyl ketene dimer:steric acid cationic emulsion prepared asdescribed in Example 9 above.

The suspension is stirred briefly to permit adsorption of the size bythe fibers to take place, after which the suspension is sheeted to form'handsheets. The handsheets are dried for two minutes at 230 F. and arewell sized.

EXAMPLE 13 The following illustrates another preferred method for themanufacture of sized paper. In this method the ketene dimer and the acylcompound are added to beater pulp as separate ionic emulsions ofopposite electrostatic sign.

An aqueous cationic emulsion of hexadecyl ketene dimer is prepared bythe method of Example 4. An aqueous anionic emulsion of stearic acid isprepared by intensively agitating 142 g. of stearic acid with 1500 cc.of water at 90 C. containing 0.4 g. of sodium hydroxide.

To an aqueous suspension of cellulose paper-making fibers at pH 7 isadded 0.15% of the cationic ketene dimer emulsion (emulsion solids basedon the dry weight of the fibers) followed by 0.1% of the stearic acidemulsion, on the same basis.

1 1 The paper is made into handsheets by customary procedure and isdried for 2 minutes at 230 F. Well-sized paper is obtained.

EXAMPLE 14 The effectiveness of hexadecanoyl chloride for papersizingketene dimers is illustrated by the following:

The procedure of Example 1 is repeated except that the stearic acid usedin Example 1 is replaced by a like amount of hexadecyl aldehyde andchloroform is used as solvent in place of the benzene in Example 1.Similar results are obtained.

We claim:

1. A composition consisting essentially of a papersizing ketene dimerand an effective extending amount in excess of about based on the Weightthereof, of a hydrophobic substantially water-insoluble saturatedsubstantially straight-chain acyl compound as extender therefor.

2. A composition according to claim 1 wherein the acyl compound isstearic acid.

3. A composition according to claim 1 wherein the acyl compound isstearamide.

4. A composition according to claim 1 wherein the acyl compound isdistearic anhydride.

5. A composition consisting essentially of hexadecyl ketene dimer and aneffective amount, between about 25% and 100%, based on the weightthereof, of stearic acid as exterior therefor.

6. A composition essentially composed of a paper-sizing ketene dimer andan effective amount within the range of from 10% to about 200%, based onthe weight thereof, of a hydrophobic substantially water-insolublesaturated substantially straight-chain acyl compound selected from thegroup consisting of higherfatty acids and their anhydrides, chlorides,amides and aldehydes as ex tender therefor, and an emulsifying agent forsaid composition.

7. A composition according to claim 6 wherein the acyl compound isstearic acid and the emulsifying agent is an anionic emulsifying agent.

8. A fluid aqueous emulsion of a composition according to claim 6.

9. Paper composed of cellulose fibers sized by a uniformly distributedreacted content of a paper-sizing ketene dimer and by an effectiveuniformly distributed unreaoted content, within the range of from. 10%to about 200% of the weight of said ketene dimer, of a hydropho bicsubstantially water-insoluble saturated substantially straight-chainacyl compound selected from the group consisting of higher fatty acidsand their anhydrides, chlorides, amides and aldehydes as extendertherefor.

10. Paper composed of cellulose fibers sized by a uniformly distributedreacted content of hexadecyl ketene dimer and by an effective uniformlydistributed unreacted content, within the range of from 10% to about200% of the weight of said ketene dimer, of stearic acid as extendertherefor.

11. In the manufacture of sized paper, wherein a paper-sizing ketenedimer is deposited on cellulose fibers as sizing agent and said fibersare heated at a temperature between about 200 F.250 F., the improvementwhich comprises depositing on said fibers along With said ketene dimeran effective extending amount, in excess of about 10% based on theweight of said ketene dimer, of a hydrophobic saturated substantiallywater-insoluble substantially straight-chain acyl compound as extendertherefor.

12. In the manufacture of sized paper, wherein an aqueous emulsion of apaper-sizing ketene dimer is added as sizing agent to an aqueoussuspension of cellulose paper-making fibers, said fibers are sheeted toform a water-laid web, and said web containing said ketene dimer isdried at a temperature in the range of about 200 F.- 250 F., theimprovement which comprises adding to said suspension an effectiveamount within the range of from 10% to about 200%, based on the weightof said ketene dimer, of a hydrophobic substantially water-insolublesaturated substantially straight-chain acyl compound selected from thegroup consisting of higher fatty acids and their anhydrides, chlorides,amides and aldehydes in aqueous emulsion state as extended for saidketene dimer.

13. A process according to claim 12 wherein said ketene dimer and saidacyl compound are added as a single cellulose-substantive cationicemulsion.

14. A process according to claim 12, wherein said ketene dimer and saidacyl compound are added as separate emulsions.

15. In the manufacture of sized paper wherein an aqueous suspension ofpaper-making cellulose fibers is formed, said fibers are renderedcationic, said fibers are sheeted to form a water-laid web, and said webis dried at a temperature between 200 F. and 250 F., the improvementwhich comprises adding to said suspension a small but effectiveamount'as sizing agent of an aqueous anionic emulsion of a mixture of apaper-sizing ketene dimer and an effective amount within the range offrom 10% to about 200%, based on the weight of said ketene dimer, of ahydrophobic substantially water-insoluble saturated straight-chain acylcompound selected from the group consisting of higher fatty acids andtheir anhydrides, chlorides, amides and aldehydes as extender therefor.

16. A process according to claim 15, wherein the weight of said acylcompound is between about 25% and of the weight of said ketene dimer andthe web is maintained at said drying temperature until at least half ofthe ultimate sizing of said ketene dimer has developed.

References Cited by the Examiner UNITED STATES PATENTS 2,901,371 8/1959Arlt 106243 DONALL H. SYLVESTER, Primary Examiner.

S. L. BASHORE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,311,532 March 28, 1967 Russell Joseph Kulick et al.

It is certified that error appears in the above identified 7 patent andthat said Letters Patent are hereby corrected as -show'n below:

Column 2, line 21, "of" should read on Column 3, line 47,

"ketent" should read ketene line 57, "along should read alone Column 10,line 52 "steric should read stearic Column 11, line 28, "exterior"should read extender Column 12, line 23, "extended" should read extenderSigned and sealed this 7th day of April 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

1. A COMPOSITION CONSISTING ESSENTIALLY OF A PAPERSIZING KETENE DIMERAND AN EFFECTIVE EXTENDING AMOUNT IN EXCESS OF ABOUT 10%, BASED ON THEWEIGHT THEREOF, OF A HYDROPHOBIC SUBSTANTIALLY WATER-INSOLUBLE SATURATEDSUBSTANTIALLY STRAIGHT-CHAIN ACYL COMPOUND AS EXTENDER THEREFOR. 9.PAPER COMPOSED OF CELLULOSE FIBERS SIZED BY A UNIFORMLY DISTRIBUTEDREACTED CONTENT OF A PAPER SIZING KETENE DIMER AND BY AN EFFECTIVEUNIFORMLY DISTRIBUTED UNREACTED CONTENT, WITHIN THE RANGE OF FROM 10% TOABOUT 200% OF THE WEIGHT OF SAID KETENE DIMER, OF A HYDROPHOBICSUBSTANTIALLY WATER-INSOLUBLE SATURATED SUBSTANTIALLY STRAIGHT-CHAINACYL COMPOUND SELECTED FROM THE GROUP CONSISTING OF HIGHER FATTY ACIDSAND THEIR ANHYDRIDES, CHLORIDES, AMIDES AND ALDEHYDES AS EXTENERTHEREFOR.